1. Field of the Invention
This invention pertains to the field of liquid dispensing equipment. More particularly, it pertains to a novel hub that facilitates mechanical connection of a nozzle. The hub provides a positive locking, tool-less connection to the nozzle core that is separable. Used cores can be removed from the hub, discarded and a new core inserted. The hub is retained and not consumed. Institution of this approach to nozzle design can realize a large gain in financial advantage over competitive products.
2. Description of the Prior Art
Needle or nozzle hubs are used to provide a positive connection of a nozzle to a source of fluid. A variety of different manufacturing processes are used in the industry to build the hub component, machining, casting, molding and insert molding are just a few examples. In every case the connection between the passage that fluid flows through in route to the exit aperture is joined, bonded, machined as one piece or otherwise designed to be an integral feature or permanent connection. The method of joining the hub to the fluid path and material selected are a function of the general type of nozzle.
At present there are three general types of nozzles used to underfill electronic devices with viscous liquid: (1) a modified hypodermic needle made of stainless steel and medical tubing, (2) a custom machined metal nozzle, and (3) a molded plastic cone-shaped nozzle. The modified hypodermic needle nozzle is merely a standard hypodermic needle adapted to fit to a standard valve (Luer or Luer lock type) and attached to a hose leading from a pump that is connected to a reservoir of liquid. Modified hypodermic needles have a constant diameter throughout the length. This causes a very high-pressure drop across the needle and restricts liquid flow. In addition, the needle is made from stainless steel, plastic, or brass. Stainless steel and plastic are not known as good heat transfer materials. The fluid path is not contiguous and usually constrictive at the connection point, hub and fluid path are permanently connected together. Transition points of the flow channel through the nozzle using this manufacturing technique are abrupt and inconsistent.
The custom machined nozzle may be made of better heat transfer materials and may be shaped to remove, or, at least, greatly reduce the resistance produced in the hypodermic needle design; however, a machined nozzle is limited to the size of the tools that can be used to cut the inside wall diameter and the wall thickness that must be maintained to ensure cuts are made without deformation of the nozzle. Machining of nozzles can be applied to one and two-piece designs, any shape can be made that can be programmed to cut using computer controlled lathes or form tools ground for the purpose. Whether the nozzle is constructed from multiple parts or machined as one with hub features integrated into the part, it is important to note, the hub cannot be separated or removed from the nozzle. It is difficult to make very small gage sizes, almost impossible if the nozzle wall is thin. These limitations, along with the high cost of machining minute nozzles of this type, have slowed the widespread use of such nozzles in the industry.
The molded plastic nozzle is the lowest cost nozzle produced. It can be made in a variety of sizes and shapes out of a number of engineering polymers, using plastic injection molding. Injection molding is a process that imposes limitations in wall thickness, due to the difficulty of forcing molten thermoplastic into the mold cavity. Plastics are not good agents of heat transfer, they are not dimensionally stable, require a relatively loose tolerance, expand and contract when exposed to high intermittent pressures and have a hub that is integral to the fluid path with threads that have little resistance to failure by over tightening. Such a practice has not been well accepted in the industry. The modified hypodermic needle remains the most widely used nozzle.
3. Objects and Advantages
Accordingly, the design of the contiguous nozzle core hub has inherent objects and advantages that were not described earlier in my patent. Several additional objects and advantages of the present invention are:
1.) To provide a design for a separable or removable hub to enable contiguous nozzle cores to be held in place and positively locked onto the output port of a pump or source of fluid.
2.) To provide a design for a nozzle or needle hub that increases the structural rigidity of a nozzle core by increasing resistance to hoop stress due to pressure. Hoop stress is a result of force from internal pressure acting on the interior surface area of the nozzle core. As stress in the core wall builds from increasing pressure, a unit strain or deflection in the hoop or circumferential direction is experienced at the core wall.
3.) To provide a design for a nozzle or needle hub that allows the core to be removed and inserted into the hub with ease, in a manner that requires no tools to accomplish.
4.) To provide a design for a nozzle or needle hub that can be produced, using thermally efficient, conductive metals, copper and copper alloys are the best candidates for the process.
5.) To provide a design that enables production of a nozzle or needle hub, wherein the design lowers cost by virtue of reduction in the number of secondary operations required to produce a saleable nozzle or needle dispensing system that is high quality and low cost to proliferate the use of the technology in the industry.
6.) To provide a design, wherein hub material and volume are selected to provide a thermal reservoir. Changes in material, volume and the heated area affect thermal energy storage rates. The speed of thermal energy dissipation into the actual nozzle is a function of the contact area and resistance caused by the gas layer between the parts in conductive heat transfer. Thermal energy transfer into the hub for a given thermal cycle can be demonstrated by Adam's model for 3 dimensional heat transfer.
7.) To provide a design for a nozzle/needle hub that contains the link for mechanical connection of a heating device.
8.) To provide a design for a nozzle/needle hub with a Standard Luer-Lok thread and 360° of engagement that reduces device damage from thread failure and process interruption from tip loosening.
9.) To provide a Universal Hex design hub for a needle/nozzle that can use standard or metric tools for removal: 8 mm metric or 5/16 standard.
10.) To provide a nozzle system that effectively reduces the amount of hazardous waste that results from dispensing related operations in the industry by 90%.
11.) To provide a tool-less method of core removal from the connection.